Restenosis of endovascular stents from stent compression

Adjunctive Utilization of Intravascular Ultrasound in Peripheral Arterial Disease Treatment

BACKGROUND

The utility and benefit of intravascular ultrasound (IVUS) has been well established in coronary interventions, however widespread adoption for peripheral interventions has lagged. The objectives of this review article were to discuss the technical components of IVUS, describe key learning pearls for IVUS utilization, and review the literature describing the clinical outcomes of endovascular peripheral arterial interventions using IVUS.

METHODS

A scoping review of the current literature utilizing Pubmed. Terms used to search the literature included "intravascular ultrasound (IVUS)" in conjunction with "peripheral arterial disease (PAD)," "endovascular interventions," "chronic limb threatening ischemia," "balloon angioplasty" "stenting," "percutaneous coronary intervention," and "outcomes." All types of articles were reviewed including review articles, retrospective reviews, meta-analyses, and prospective observational and randomized studies.

RESULTS

Published literature regarding IVUS use in peripheral arterial interventions is heterogeneous and limited to mainly retrospective studies, registry analyses and metanalyses. Outcomes are generally favorable with the adjunct of IVUS compared to traditional angiography-driven peripheral interventions. The addition of IVUS improves stent expansion, stent patency, and reduces reintervention rates, particularly in infrainguinal arterial lesions. Long-term costs may also be lower with IVUS-guided procedures.

CONCLUSIONS

Expert consensus largely supports the implementation of IVUS in endovascular interventions for peripheral arterial disease. However, more robust high-quality data evaluating the efficacy, durability, and cost of IVUS in peripheral arterial disease are still needed.

Intravascular Ultrasound Use in Peripheral Arterial and Deep Venous Interventions: Multidisciplinary Expert Opinion From SCAI/AVF/AVLS/SIR/SVM/SVS

Percutaneous revascularization is the primary strategy for treating lower extremity venous and arterial disease. Angiography is limited by its ability to accurately size vessels, precisely determine the degree of stenosis and length of lesions, characterize lesion morphology, or correctly diagnose postintervention complications. These limitations are overcome with use of intravascular ultrasound (IVUS). IVUS has demonstrated the ability to improve outcomes following percutaneous coronary intervention, and there is increasing evidence to support its benefits in the setting of peripheral vascular intervention. At this stage in its evolution, there remains a need to standardize the use and approach to peripheral vascular IVUS imaging. This manuscript represents considerations and consensus perspectives that emerged from a roundtable discussion including 15 physicians with expertise in interventional cardiology, interventional radiology, and vascular surgery, representing 6 cardiovascular specialty societies, held on February 3, 2023. The roundtable's aims were to assess the current state of lower extremity revascularization, identify knowledge gaps and need for evidence, and determine how IVUS can improve care and outcomes for patients with peripheral arterial and deep venous pathology.

Appropriate Use of Intravascular Ultrasound During Arterial and Venous Lower Extremity Interventions

BACKGROUND

There has been growing use of intravascular ultrasound (IVUS) during lower extremity arterial and venous revascularization. Observational data suggest that the use of IVUS can improve periprocedural and long-term outcomes, but largescale prospective data remain limited. Consensus opinion regarding the appropriate use of IVUS during peripheral intervention is needed.

OBJECTIVES

The purpose of this consensus document is to provide guidance on the appropriate use of IVUS in various phases of peripheral arterial and venous interventions.

METHODS

A 12-member writing committee was convened to derive consensus regarding the appropriate clinical scenarios for use of peripheral IVUS. The group iteratively created a 72-question survey representing 12 lower extremity arterial interventional scenarios. Separately, a 40-question survey representing 8 iliofemoral venous interventional scenarios was constructed. Clinical scenarios were categorized by interventional phases: preintervention, intraprocedure, and postintervention optimization. Thirty international vascular experts (15 for each survey) anonymously completed the survey instrument. Results were categorized by appropriateness using the median value and disseminated to the voting panel to reevaluate for any disagreement.

RESULTS

Consensus opinion concluded that IVUS use may be appropriate during the preintervention phase for evaluating the etiology of vessel occlusion and plaque morphology in the iliac and femoropopliteal arteries. IVUS was otherwise rated as appropriate during iliac and femoropopliteal revascularization in most other preintervention scenarios, as well as intraprocedural and postprocedural optimization phases. IVUS was rated appropriate in all interventional phases for the tibial arteries. For iliofemoral venous interventions, IVUS was rated as appropriate in all interventional phases.

CONCLUSIONS

Expert consensus can help define clinical procedural scenarios in which peripheral IVUS may have value during lower extremity arterial and venous intervention while additional prospective data are collected.

Midterm Results of the Supera Stent for the Treatment of Femoropopliteal Occlusive Disease

BACKGROUND

The Supera (Abbott Vascular, Santa Clara, CA) stent is an interwoven nitinol, shape-memory stent with high strength and flexibility characteristics which are purported to increase resistance to kinking and compression. The purpose of this study was to review single-center outcomes of the use of this stent in the femoropopliteal segment.

METHODS

We performed a single-center, retrospective analysis of patients who underwent Supera stent placement for femoropopliteal occlusive disease from 2016-2019. Data was collected on patient demographics and procedural details. Follow-up imaging data, including duplex imaging and ankle-brachial indices, and clinical data were abstracted from encounter notes.

RESULTS

Sixty-two patients with 72 unique Supera stent placements were identified. Mean age was 76 and 69% were male. 56% of patients had severe calcification and 11% had moderate calcification. 48% of lesions were Trans-Atlantic Inter-Society Consensus Document C or D lesions. Primary patency rates at 12, 24, and 36 months were 85%, 82%, and 75%, respectively. Primary patency was not affected significantly by lesion length, degree of calcification, number of outflow vessels, concomitant interventions, or stent size.

CONCLUSIONS

These results demonstrate sustained primary patency with the Supera stent over a 3-year interval in treatment of patients with femoropopliteal occlusive disease, including in the setting of severely calcified vessels.

Intravascular ultrasound in peripheral venous and arterial interventions: A contemporary systematic review and grading of the quality of evidence

Although angiography has been the primary imaging modality used in peripheral vascular intervention, this technique has major limitations due to the evaluation of three-dimensional vessels in two dimensions. Intravascular ultrasound (IVUS) is an important adjunctive tool that can address some of these limitations. This systematic review assesses the appropriateness of IVUS as an imaging modality for guiding peripheral intervention through evidence collection and clinical appraisal of studies. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a cohort of 48 studies (29 arterial; 19 venous) detailing IVUS use in peripheral vascular intervention were extracted. Qualitative assessment of the studies evaluated pre- and postprocedure efficacy of IVUS and revealed that IVUS-guided peripheral intervention in arterial and venous diagnosis and treatment was superior to other imaging techniques alone. Each study in the cohort was further assessed for reliability and validity using the Oxford Centre for Evidence Based Medicine (CEBM) level of evidence scale. The majority of both arterial (79.3%) and venous (73.7%) studies received a 2b rating, the second highest level of evidence rating. The evidence to date indicates that IVUS results in better clinical outcomes overall and should be more widely adopted as an adjunctive imaging modality during peripheral intervention. (PROSPERO Registration No.: CRD42021232353).

Non-ST elevation myocardial infarction and ischaemic cardiomyopathy due to extrinsic tumour compression of left internal mammary artery graft-obtuse marginal with fibrosis due to chest wall radiation: a case report

Background

Cardiovascular disease and cancer remain the most prevalent conditions worldwide. The relationship between the two is becoming increasingly recognized, with both sharing similar risk factors. Currently, there are no guidelines or substantial data for the management of this subset of patients. This case presents the management of a patient with advanced malignancy and ischaemic cardiomyopathy, exploring the difficult decision making process for revascularization, ensuring an individualized approach is used for each patient.

Case summary

A 68-year-old man with Stage II lung cancer and overall poor prognosis with multiple comorbidities limiting his functional status presented with a non-ST elevation myocardial infarction and ischaemic cardiomyopathy due to extrinsic tumour compression and left internal mammary artery graft-obtuse marginal fibrosis due to chest wall radiation. He had a prolonged admission with the heart team discussions regarding optimal management. He subsequently underwent percutaneous coronary intervention to his native left circumflex chronic total occlusion. He was discharged home on dual antiplatelet and heart failure therapy.

Discussion

This case reflects that the management of patients with cancer and coronary artery disease is complex. Many factors including patient comorbidities adversely impact on prognosis, and treatment goals need to be clearly defined. The evidence in the area is lacking but continues to grow; however, the care for such patients needs to be individualized.

Two-Step Geometry Design Method, Numerical Simulations and Experimental Studies of Bioresorbable Stents

The stent-implantation process during angioplasty procedures usually involves clamping the stent onto a catheter to a size that allows delivery to the place inside the artery. Finding the right geometrical form of the stent to ensure good functionality in the open form and to enable the clamping process is one of the key elements in the stent-design process. In the first part of the work, an original two-step procedure for stent-geometry design was proposed. This was due to the necessary selection of a geometry that would provide adequate support to the blood-vessel wall without causing damage to the vessel. Numerical simulations of the crimping and deployment processes were performed to verify the method. At the end of this stage, the optimal stent was selected for further testing. In addition, numerical simulations of selected experimental tests (catheter-crimping process, compression process) were used to verify the obtained geometrical forms. The results of experimental tests on stents produced by the microinjection method are presented. The digital image correlation (DIC) method was used to compare the results of numerical simulation and experimental tests. The two-step modeling approach was found to help select the appropriate geometry of the expanded stent, which is an extremely important step in the design of the crimping process. In the part of the paper where the results obtained by numerical simulation were compared with those gained by experiment and using the DIC method, a good compatibility of the displacement results can be observed. For both longitudinal and transverse (pinch) stent compression, the results practically coincide. The paper presents also the application of the DIC method which significantly expands the research possibilities, allowing for a detailed inspection of the deformation state and, above all, verification of local dangerous areas. This approach significantly increases the possibility of assessing the quality of the stents.

[Interventional Treatments for Femoropopliteal Arterial Disease and Recent Updates]

Peripheral arterial occlusive disease (PAOD) of the femoropopliteal artery is commonly caused by atherosclerosis. It can present with varying clinical symptoms depending on the degree of disease, ranging from intermittent claudication to critical limb ischemia and tissue loss. Therefore, appropriate and timely treatment is required to improve symptoms and salvage the affected limbs. Interventional approaches for femoropopliteal arterial disease commonly include percutaneous transluminal angioplasty, atherectomy, and stent placement. Over the years, endovascular recanalization has been widely performed for treating PAOD due to continuous developments in its techniques and availability of dedicated devices with the inherent advantage of being minimal invasive. In this review, we introduce various types of endovascular treatment methods, discuss the results of clinical research from existing literature, and illustrate the treatment procedures using representative images.

The Effects of Pro-Inflammatory and Anti-Inflammatory Agents for the Suppression of Intimal Hyperplasia: An Evidence-Based Review

Anti-atherogenic therapy is crucial in halting the progression of inflammation-induced intimal hyperplasia. The aim of this concise review was to methodically assess the recent findings of the different approaches, mainly on the recruitment of chemokines and/or cytokine and its effects in combating the intimal hyperplasia caused by various risk factors. Pubmed and Scopus databases were searched, followed by article selection based on pre-set inclusion and exclusion criteria. The combination of keywords used were monocyte chemoattractant protein-1 OR MCP-1 OR TNF-alpha OR TNF-α AND hyperplasia OR intimal hyperplasia OR neointimal hyperplasia AND in vitro. These keywords combination was incorporated in the study and had successfully identified 77 articles, with 22 articles were acquired from Pubmed, whereas 55 articles were obtained from Scopus. However, after title screening, only twelve articles meet the requirements of defined inclusion criteria. We classified the data into 4 different approaches, i.e., utilisation of natural product, genetic manipulation and protein inhibition, targeted drugs in clinical setting, and chemokine and cytokines induction. Most of the articles are working on genetic manipulation targeted on specific pathway to inhibit the pro-inflammatory factors expression. We also found that the utilisation of chemokine- and cytokine-related treatments are emerging throughout the years. However, there is no study utilising the combination of approaches that might give a better outcome in combating intimal hyperplasia. Hopefully, this concise review will provide an insight regarding the usage of different novel approaches in halting the progression of intimal hyperplasia, which serves as a key factor for the development of atherosclerosis in cardiovascular disease.

Results of Stenting for Central Venous Occlusions and Stenoses in the Hemodialysis Patients

Objectives: We aim to investigate the results of stenting for central venous occlusions and stenoses in the hemodialysis patients.

Methods: Twenty-nine cases treated with endovascular recanalization with deployment of bare metal stent (BMS) for central venous occlusions (24 cases) and recurrent stenoses (5 cases) between 2014 and 2018 were retrospectively analyzed. Results of these procedures including success rate, operative time, estimated blood loss, morbidity, primary patency, assisted primary patency and freedom from target-lesion revascularization (TLR) were evaluated.

Results: Nine lesions were in brachiocephalic vein (Occlusion/Stenosis: 8/1) and 20 lesions were in subclavian vein (Occlusion/Stenosis: 16/4). Procedural success was 94% (29/31 cases) and operation time/estimated blood loss was 68±39 min/28±54 g. Symptom were relieved or disappeared in all successful cases. Morbidity (extravasation of contrast medium) was 3% (1/29). During the period of observation, 1 stent fracture with occlusion and 1 stent migration to periphery were recognized. 1-year primary patency, freedom from TLR, and assisted primary patency were 40% (median patent time: 256 days), 67% (median patent time: 524 days), and 77%, respectively.

Conclusion: Stenting for central venous occlusions and stenoses in the hemodialysis patients is safe and durable treatment option. However, considering its off-label use and potential hazard including vessel rupture, stent migration, and stent fracture, the indication for BMS deployment should be conservative, and interventionist should be well acquainted with prevention and measures to these complications. (This is a translation of Jpn J Vasc Surg 2019; 28: 193–198.)

Delayed Stroke after Aneurysm Treatment with Flow Diverters in Small Cerebral Vessels: A Potentially Critical Complication Caused by Subacute Vasospasm

Flow diversion (FD) is a novel endovascular technique based on the profound alteration of cerebrovascular hemodynamics, which emerged as a promising minimally invasive therapy for intracranial aneurysms. However, delayed post-procedural stroke remains an unexplained concern. A consistent follow-up-regimen has not yet been defined, but is required urgently to clarify the underlying cause of delayed ischemia. In the last two years, 223 patients were treated with six different FD devices in our center. We identified subacute, FD-induced segmental vasospasm (SV) in 36 patients as a yet unknown, delayed-type reaction potentially compromising brain perfusion to a critical level. Furthermore, 86% of all patients revealed significant SV approximately four weeks after treatment. In addition, 56% had SV with 25% stenosis, and 80% had additional neointimal hyperplasia. Only 13% exhibited SV-related high-grade stenosis. One of those suffered stroke due to prolonged SV, requiring neurocritical care and repeated intra-arterial (i.a.) biochemical angioplasty for seven days to prevent territorial infarction. Five patients suffered newly manifested, transient hemicrania accompanying a compensatorily increased ipsilateral leptomeningeal perfusion. One treated vessel obliterated permanently. Hence, FD-induced SV is a frequent vascular reaction after FD treatment, potentially causing symptomatic ischemia or even stroke, approximately one month post procedure. A specifically early follow-up-strategy must be applied to identify patients at risk for ischemia, requiring intensified monitoring and potentially anti-vasospastic treatment.

Drug-Coated Balloon Angioplasty in Atherosclerosis Patients With Popliteal Artery Involvement

Purpose: To investigate outcomes of drug-coated balloon (DCB) angioplasty in endovascular interventions including or restricted to the popliteal artery. Methods: A retrospective analysis was conducted of 266 patients [median age 72 years, interquartile range (IQR) 62, 78; 166 men] treated with DCB angioplasty in 281 de novo lesions including the popliteal artery between December 2011 and January 2015 at a single center. The median lesion length was 270 mm (IQR 150, 373). The study outcomes were primary patency and predictors of restenosis [reported as the hazard ratio (HR) with 95% confidence interval (CI)]. Results: The primary patency was 77.4% at a median 12.2 months (IQR 5.7, 18.8). Independent variables associated with restenosis included baseline Rutherford category (HR 1.36, 95% CI 1.05 to 1.77, p=0.02), reference vessel diameter (HR 0.77, 95% CI 0.63 to 0.95, p=0.02), dissection (HR 1.69, 95% CI 1.022.79, p=0.04), and standard nitinol stent use (HR 2.08, 95% CI 1.14 to 3.79, p=0.02). Conclusion: Outcomes after DCB angioplasty in lesions including the popliteal artery were acceptable compared with previous studies. Further investigation with long-term follow-up is needed to confirm these results.

[Graft aneurysms as long-term complication of polyester prostheses and their management : Brief review based on a systematic review of the literature]

INTRODUCTION

A material-associated true aneurysm after previous use of a vascular prosthesis for arterial reconstruction mostly in peripheral arterial occlusion disease (PAOD) is considered a rare but serious complication.

AIM AND METHOD

The aim of the compact brief review was to describe the rare finding of a true aneurysm of a prosthesis and its diagnosis-specific care including a representative scientific case report, based on selected topic-related references from the medical literature as well as the specific experiences obtained from the successful clinical management in single cases. RESULTS (COMPLEX KEY POINTS ASSOCIATED WITH PATIENT AND CLINICAL FINDINGS AND CASE PRESENTATION): Out of initially 321 references found in the literature search, 20 articles published after 1995 were finally evaluated. Most frequently, pseudoaneurysms of knitted polyester prostheses at the femoropopliteal segment occurred on average after approximately 12.9 years. In one third of the cases two or more aneurysms of Dacron prostheses were described. Histological and electron microscopy investigations revealed mainly breakage of filaments and foreign body reactions. In more than half of the patients, the aneurysm was resected and for reconstruction an interposition graft was implanted. Complete removal of the prosthesis and endovascular treatment were only second choice.

REPRESENTATIVE CASE

A 49-year-old male patient underwent a femoropopliteal P1 prosthetic bypass of the right leg in 1997. After 19 years a true aneurysm of the prosthesis was diagnosed in the right thigh using duplex ultrasonography and complementary magnetic resonance angiography (MRA). This was successfully treated with resection of the aneurysm and insertion of an 8‑mm Dacron prosthesis (Intergard Synergy Knitted, InterVascular, Bensheim, Germany).

CONCLUSION

The development of true aneurysms of prostheses has not yet been satisfactorily clarified. This belongs to the profile of late complications, even if rarely and should be controlled after a postoperative interval of approximately one decade. This should be carried out by diagnostic imaging follow-up screening if the previous arterial recanalization/reconstruction could not be performed sequentially following endovascular intervention and venous-based reconstruction, other than with prosthetic material.

Mid-Term Outcomes of Stent Overlap in Long Total Occluded Lesions of Superficial Femoral Artery

Background

Superficial femoral artery chronic total occlusion (SCTO) is a common type of peripheral arterial disease (PAD). Endovascular therapy is a treatment approach that has a poor long-term success rate in this group. The aim of this study was to compare the mid-term results of two different uses of nitinol stents in long SCTO lesions (>100 mm): the use of one long stent or two shorter stents.

Material/Methods

Of 154 patients who underwent percutaneous infrainguinal interventions from 2011 to 2014, a total of 170 CTO lesions were selected for this retrospective study analysis. The mean age of the study population was 63.4±10.4 years (range 29–89 years); 71.8% of the patients were male.

Results

Patients were divided into two groups according to the number of stents used. Patients treated with a single stent were placed into group A and patients treated with two stents were placed into group B. The stent fracture rate was significantly higher in group B compared to group A (29.2% vs. 42%). Type 1 and 2 fracture rates were higher in group A, but type 3 and 5 fracture rates were significantly higher in group B. The rate of stent restenosis was significantly higher in group B compared to group A (45.1% vs. 54.5%, p=0.05).

Conclusions

Mid-term patency rate was low in patients with long totally occluded superficial femoral artery (SFA) lesions. Using a long single stent had an acceptable mid-term patency rate compared to using a two stent strategy. Stent fracture seemed to be the main reason for in-stent restenosis in cases of multiple stenting. A long single stent strategy may be more appropriate and reasonable than a two stent strategy in the treatment of long SFA lesions.

Limitations of Percutaneous Transluminal Angioplasty and Stenting for the Treatment of Disease of the Superficial Femoral and Popliteal Arteries

The long-term primary patency rates for percutaneous transluminal angioplasty (PTA) and stenting in treatment of disease of the superficial femoral and popliteal arteries have been disappointing. Three-year primary patency rates of ∼50% have been reported for PTA and first-generation stents. Early results with newer nitinol stents appear promising; however, long-term data are lacking. One- and 2-year primary patency rates of 76% to 97% and 60% to 84%, respectively, have been reported with nitinol stents. An emerging concern with nitinol stents is the frequency of stent fracture (≥25%) after interventions for long-segment disease. A recent study has shown that stent fractures are associated with in-stent restenosis and with significantly lower primary patency at 1 year.

The therapeutic success of PTA and stenting correlates with the complexity of the underlying disease. The best results are achieved when treating focal stenoses in patients with good distal runoff. Because endovascular interventions are preferred by patients, can be repeated, and preserve the option of bypass surgery, PTA and stenting are increasingly employed for diffuse and complex SFA disease. Clarifying the role of PTA and stenting in the treatment of complex SFA disease will require future studies that stratify results by both lesion anatomy and treatment indication.

Subclavian Stents and Stent-Grafts: Cause for Concern?

Purpose:

To report cases of stent and stent-graft fracture in the subclavian vessels.

Methods and Results:

Three patients with self-expanding stents of 3 different types in 1 subclavian artery and 2 subclavian veins presented with recurrent symptoms 6 months to 2 years after stenting. All devices showed signs of compression with stent fracture. The covered stent in the subclavian artery was excised. Of the 2 venous patients, 1 was treated with first rib resection and the other refused further treatment.

Conclusions:

The subclavian vessels are prone to flexion during movement, and the vessels may be compressed by external structures, including the clavicle and first rib. Stents that have not been designed to withstand these forces may be damaged.

Deformation of Self-Expanding Stent-Grafts Complicating Endovascular Peripheral Aneurysm Repair

Purpose:

To demonstrate the deformation of self-expandable stents after endovascular repair of peripheral aneurysms.

Methods and Results:

The Corvita Endoluminal Graft was used to treat a traumatic false aneurysm of the right subclavian artery and a common iliac artery aneurysm in 2 patients. In the subclavian case, the stent-graft showed a “cigar-shaped” deformation with hemodynamically significant stenoses at the proximal and distal ends at 3 months. In the second case, the same type of deformity was noted only 1 day after implantation. Two months later, the stent-graft occluded, necessitating surgical repair.

Conclusions:

Both cases demonstrate the possibility of stent deformation of self-expanding stent-grafts implanted at arterial sites not subject to external compression.

Response of Renal and Femoropopliteal Arteries to Palmaz Stent Implantation Assessed with Intravascular Ultrasound

Purpose:

To establish the processes responsible for late lumen loss in renal and femoropopliteal Palmaz stents using intravascular ultrasound (IVUS).

Methods:

The first 7 consecutive patients treated with stents for renal (n = 4) and femoropopliteal (n = 3) arterial occlusive disease were studied with IVUS immediately after angiographically successful stent placement (< 10% residual stenosis) and periodically during follow-up. Images of both stent edges and the most stenotic site inside the stent at follow-up were matched to the same cross sections captured immediately after stent placement for quantitative analysis.

Results:

Late lumen loss in renal artery stents at 5 to 34 months was considerably less than in femoropopliteal stents (17% versus 62%, respectively). In the renal location, late lumen loss (3.0 ± 1.3 mm2) was due to neointimal hyperplasia, whereas stent area remained unchanged (3% decrease). Late lumen loss (7.4 ± 8.2 mm2) in femoropopliteal stents was due to neointimal hyperplasia and stent area reduction (26%). Overall, in both types of arteries, neointimal development and stent area reduction were larger at the most stenotic site than at the stent edges.

Conclusions:

These data suggest that there may be differences between renal and femoropopliteal arteries in the extent of hyperplastic response to stents.

A computational study of stent performance by considering vessel anisotropy and residual stresses

Finite element simulations of stent deployment were carried out by considering the intrinsic anisotropic behaviour, described by a Holzapfel-Gasser-Ogden (HGO) hyperelastic anisotropic model, of individual artery layers. The model parameters were calibrated against the experimental stress-stretch responses in both circumferential and longitudinal directions. The results showed that stent expansion, system recoiling and stresses in the artery layers were greatly affected by vessel anisotropy. Following deployment, deformation of the stent was also modelled by applying relevant biomechanical forces, i.e. in-plane bending and radial compression, to the stent-artery system, for which the residual stresses generated during deployment were particularly accounted for. Residual stresses were found to have a significant influence on the deformation of the system, resulting in a re-distribution of stresses and a change of the system flexibility. The results were also utilised to interpret the mechanical performance of stent after deployment.

Comparison of long-term patency after endovascular therapy for superficial femoral artery occlusive disease between patients with and without hemodialysis

OBJECTIVE

To compare long-term patency after endovascular therapy (EVT) for superficial femoral artery (SFA) occlusive disease between patients with hemodialysis (HD; HD+) and those without HD (HD-).

BACKGROUND

Long-term patency after EVT for SFA occlusive disease in HD+ remains unknown.

METHODS

EVT to SFA was successfully performed in 382 consecutive patients during 2004-2011. Cox proportional hazard model estimated the hazard ratio (HR) for the loss of primary patency (PP), secondary patency (SP), and amputation-free survival (AFS) in HD+. Binominal logistic regression analysis calculated the propensity score (PS) for covariates with a P value of <0.2 for HD as a dependent variable. HRs were adjusted for PS in multivariate analysis using the Cox proportional hazard model.

RESULTS

PP and SP in HD+ and HD- were 47.9 and 79.4% and 68.4 and 92.5%, respectively, 4 years after EVT. There were no procedure-related amputations or in-hospital deaths. Adjusted HRs for the loss of PP, SP, and AFS were as follows: loss of PP, adjusted HR 2.010, 95% CI 1.157-3.492, P = 0.013; loss of SP, adjusted HR 2.927, 95% CI 1.236-6.933, P = 0.015; and loss of AFS, adjusted HR 1.665, 95% CI 0.994-2.791, P = 0.053.

CONCLUSIONS

Although HD+ had more than double the risks for loss of PP and SP than HD-, EVT to SFA in HD+ was found to be safe with an acceptable PP and SP. © 2015 Wiley Periodicals, Inc.

Auxetic coronary stent endoprosthesis: fabrication and structural analysis

BACKGROUND

Cardiovascular heart disease is one of the leading health issues in the present era and requires considerable health care resources to prevent it. The present study was focused on the development of a new coronary stent based on novel auxetic geometry which enables the stent to exhibit a negative Poisson's ratio. Commercially available coronary stents have isotropic properties, whereas the vascular system of the body shows anisotropic characteristics. This results in a mismatch between anisotropic-isotropic properties of the stent and arterial wall, and this in turn is not favorable for mechanical adhesion of the commercially available coronary stents with the arterial wall. It is believed that an auxetic coronary stent with inherent anisotropic mechanical properties and negative Poisson's ratio will have good mechanical adhesion with the arterial wall.

METHODS

The auxetic design was obtained via laser cutting, and surface treatment was performed with acid pickling and electropolishing, followed by an annealing process. In vitro mechanical analysis was performed to analyze the mechanical performance of the auxetic coronary stent. Scanning electronic microscopy (SEM) was used to determine the effects of fabrication processes on the topography of the auxetic stent.

RESULTS AND CONCLUSIONS

The elastic recoil (3.3%) of the in vitro mechanical analysis showed that the auxetic stent design effectively maintained the luminal patency of the coronary artery. Also, the auxetic coronary stent showed no foreshortening, therefore it avoids the problem of stent migration, by expanding in both the radial and longitudinal directions. By virtue of its synclastic behavior, the auxetic stent bulges outward when it is radially expanded through an inflated balloon.

Value of C-Arm Computed Tomography to Evaluate Stent Deployment During Femoro-Popliteal Revascularization

PURPOSE

To compare the accuracy of C-arm computed tomography (CT) and digital subtraction angiography (DSA) in detecting incomplete stent expansion (ISE) after superficial femoral artery (SFA) stenting using intravascular ultrasound (IVUS) as a gold standard.

MATERIALS

Fifty patients with symptomatic SFA occlusive disease requiring angioplasty were prospectively included. Once technical success (<30 % residual stenosis) was obtained on post-procedural DSA, C-arm CT and IVUS were acquired. DSA and C-arm CT examinations were reviewed by 2 investigators and correlated with IVUS. C-arm CT image quality was rated on a four-point scale. Doppler ultrasound was performed at 1-year follow-up.

RESULTS

The ankle-brachial index was 0.69 ± 0.10 and 0.99 ± 0.40, respectively, pre- and post-procedure. C-arm CT imaging quality was rated as good or excellent in 80%. In-stent minimal luminal diameter (MLD) was evaluated at 4.71 ± 0.7 mm on DSA, 3.39 ± 0.6 mm on IVUS, and 3.12 ± 0.9 mm on C-arm CT. Compared to IVUS, DSA demonstrated an overestimation of MLD (p = 0.0001), an underestimation of ISE (DSA = 18.8% ± 7.6; IVUS = 29.8% ± 9) (p < 0.0001), and a poor inter-technique intra-class correlation coefficient (ICC = 0.24). No difference was observed between IVUS and C-arm CT in ISE as calculated by diameter (29.8 ± 9 vs. 28.2 ± 12.5%, p = 0.5) and area (30.2 ± 8.4 vs. 33.3 ± 9.5%, p = 0.2). Inter-technique ICC between C-arm CT and IVUS was 0.72 [95%CI 0.49; 0.85] for MLA measurements. The inter-observer ICC for MLD and MLA measurements on C-arm CT were, respectively, estimated at 0.75 [95% CI 0.40, 0.89] and 0.77 [95% CI 0.43, 0.90)].

CONCLUSIONS

C-arm CT presents a better correlation with IVUS than DSA to determine lumen diameter and ISE immediately after percutaneous revascularization.

Subclavian transectional stent fracture and migration to the aortic carrefour: a case description of retrieval by snare system

Percutaneous transluminal angioplasty with or without stent has become the treatment of choice for stenotic lesion in subclavian arteries. However, there is a growing concern following many reports of stent fractures, a serious complication of endovascular therapy. We report for the first time a case of delayed left subclavian stent fracture with transection of the protruding ostial part and migration into the aortic carrefour that was retrieved by a snare device.

Endovascular Treatment of the Common Femoral Artery for Limb Ischemia

Objective:

To determine the short- and mid-term outcomes of percutaneous endovascular common femoral artery (CFA) revascularization (eCFR) of the CFA.

Methods:

A review of patients who underwent eCFR for limb ischemia between 2006 and 2012 was performed. Limb salvage, patient survival, survival free from reintervention, and survival free from amputation rates were determined. Median (range) follow-up was 28 (1-71) months.

Results:

In all, 115 patients underwent 121 eCFR for CFA occlusion (n = 13) or stenosis (n = 108); 109 (90%) were technically successful and 7 (6%) had significant perioperative complications; access site hematoma (n = 2) and thromboembolism (n = 5). Thirty-day mortality and amputation rates were 2.5% and 0.8%, respectively. The 1- and 3-year limb salvage rates were 97% and 97%, respectively. The 1- and 3-year survival free from reintervention rates were 77% and 57%, respectively. The 1- and 3-year survival free from amputation rates were 84% and 70%, respectively.

Conclusion:

These novel data demonstrate that eCFR is a durable treatment for patients with limb ischemia associated with CFA disease.

Balloon-expandable stent deformation during deployment into the iliac artery: a procedural complication managed conservatively

The management of aortoiliac insufficiency has been improved considerably since the introduction of balloon-expandable stents in 1991. Although numerous studies have shown the safety and efficacy of balloon-expandable iliac artery stent placement, the procedure is not without potential complication. We report here a very unusual case of iliac artery stenting being complicated by deformation and elongation of the stent following balloon rupture at initial deployment with retention of the distal balloon marker and our successful approach to subsequent management with combined acetylsalicylic acid and clopidogrel. In conclusion, this conservative approach may be an alternative treatment of a partially deployed aortoiliac stent with a retained foreign body when further intervention is considered to be of high risk.

Intravascular ultrasound: principles and cerebrovascular applications

Intravascular sonography is a valuable tool for the morphologic assessment of coronary atherosclerosis and the effect of pharmacologic and nonpharmacologic interventions on the progression or stabilization of atherosclerosis. An analysis of the different modes, applications, and limitations is provided on the basis of review of existing data from multiple clinical case studies, trials, and mechanistic studies. Intravascular sonography has been used to assess the outcomes of different percutaneous interventions, including angioplasty and stent implantation, and to provide detailed characterization of atherosclerotic lesions, aneurysms, and dissections within the cerebrovascular circulation. Evolution of intravascular sonographic technology has led to the development of more sophisticated diagnostic tools such as color-flow, virtual histology, and integrated backscatter intravascular sonography. The technologic advancement in intravascular sonography has the potential of providing more accurate information prior, during, and after a medical or endovascular intervention. Continued assessment of this diagnostic technique in both the intracranial and extracranial circulation will lead to increased use in clinical practice with the intent to improve outcomes.

Endovascular treatment of peripheral vascular disease

Peripheral arterial disease (PAD) affects about 27 million people in North America and Europe, accounting for up to 413,000 hospitalizations per year with 88,000 hospitalizations involving the lower extremities and 28,000 involving embolectomy or thrombectomy of lower limb arteries. Many patients are asymptomatic and, among symptomatic patients, atypical symptoms are more common than classic claudication. Peripheral arterial disease also correlates strongly with risk of major cardiovascular events, and patients with PAD have a high prevalence of coexistent coronary and cerebrovascular disease. Because the prevalence of PAD increases progressively with age, PAD is a growing clinical problem due to the increasingly aged population in the United States and other developed countries. Until recently, vascular surgical procedures were the only alternative to medical therapy in such patients. Today, endovascular practice, percutaneous transluminal angioplasty with or without stenting, is used far more frequently for all types of lower extremity occlusive lesions, reflecting the continuing advances in imaging techniques, angioplasty equipment, and endovascular expertise. The role of endovascular intervention in the treatment of limb-threatening ischemia is also expanding, and its promise of limb salvage and symptom relief with reduced morbidity and mortality makes percutaneous transluminal angioplasty/stenting an attractive alternative to surgery and, as most endovascular interventions are performed on an outpatient basis, hospital costs are cut considerably. In this monograph we discuss current endovascular intervention for treatment of occlusive PAD, aneurysmal arterial disease, and venous occlusive disease.

Primary nitinol stenting for femoropopliteal disease

The 1- to 2-year primary patency rates associated with self-expanding nitinol stents for the treatment of symptomatic femoropopliteal disease are superior to those for percutaneous transluminal angioplasty (PTA) and the first-generation stainless steel balloon-expandable stents. The advantages of nitinol stents include improved radial strength and flexibility, the ability to recover from being crushed, reduced foreshortening, and (importantly) deployability without balloon dilation of the stent edge (which may decrease the incidence of the edge stenosis, or "candy-wrap" effect, often observed with balloon-expandable stents). The technical success rate associated with primary deployment of nitinol stents is very high, and acute to 6-month patency results are predictably excellent. Prior to the introduction of nitinol stents, the original guidelines (2000) of the multidisciplinary TransAtlantic Inter-Society Consensus (TASC I) recommended only an adjunctive role for femoropopliteal stents following suboptimal PTA. The abbreviated 2007 TASC II report essentially extended this recommendation to nitinol stents. Here, current trials of nitinol stenting in the femoropopliteal segment are discussed, with emphasis on the advantages of primary (and often direct) deployment in selected circumstances dependent on factors including lesion length, lesion location, indication for treatment (critical limb ischemia or claudication, in-stent restenosis, stent-graft restenosis), and the relative appropriateness of other modalities (e.g., covered stents). Technical considerations in primary nitinol stenting are briefly reviewed. Open questions regarding the factors involved in nitinol stent fracture and the possible association of fracture and restenosis are examined in the context of current clinical trials. A new generation of femoropopliteal nitinol stents combining superior durability and flexibility is expected soon. Development and implementation of uniform reporting and surveillance standards is important for optimizing current and future research.

Incidence, anatomical location, and clinical significance of compressions and fractures in infrapopliteal balloon-expandable metal stents

PURPOSE

To investigate the incidence, anatomical location, and clinical impact of fractures and/or compression of infrapopliteal balloon-expandable metal stents implanted for critical limb ischemia (CLI) treatment.

METHODS

This prospective study included 63 CLI patients (45 men; mean age 71.3+/-9.5 years) who had been treated with infrapopliteal angioplasty and stent placement for 191 lesions in 84 limbs. In all, 369 stents (296 stainless steel and 73 cobalt-chromium alloy) were implanted; 239 were placed overlapping in tandem lesions. Mean length of the overall stented segment was 4.4+/-6.3 cm (range 1.6-14.0). Stents were located in the tibioperoneal (n = 34), anterior tibial (n = 195), posterior tibial (n = 63), and peroneal (n = 77) arteries. Follow-up consisted of digital subtraction angiography and infrapopliteal radiography imaging at 2 different angles. Evaluation of stents for the presence of fracture and/or compression was done after digital processing at the highest possible magnification. Stent fractures were defined according to published standards, whereas compression was classified as severe shape alteration and/or collapse of the stent mesh. Angiographic restenosis was based on a 50% threshold.

RESULTS

Mean follow-up was 15+/-11 months (range 6-60). Image analysis detected 1 (0.3%) severe stent fracture (complete separation and misalignment of stent struts) and 11 (3.0%) stent compressions. Infrapopliteal stent fracture and compressions were associated with increased artery restenosis [100% (12/12) versus 47.3% (169/357), p<0.001] and an increased rate of clinical deterioration and clinically-driven reinterventions [41.7% (5/12 limbs) versus 19.4% (14/72 limbs), p = 0.04]. The single fracture and most of the compressions were located in the distal third of the anterior tibial artery.

CONCLUSION

Stent fractures and compressions of infrapopliteal balloon-expandable metal stents are infrequent. However, they may be related to increased restenosis.

Strut fracture: a further concern with drug-eluting stents

A potential cause of drug-eluting stent restenosis is strut fracture. To date, few cases have been reported in the available literature and a best treatment method has not been established. We describe two cases of sirolimus-eluting stent fracture combined with focal restenosis and also review those previously reported.

Vascular Remodeling After Carotid Artery Stenting

Carotid stenting is an alternative to endarterectomy for the treatment of carotid stenosis. To determine the role of vascular remodeling after stent placement, we studied 19 high surgical risk patients undergoing carotid stenting for severe stenosis. Using high-resolution ultrasound, we evaluated the intima-media thickness (IMT), the intima-intima diameter, and the adventitia-adventitia diameter at prespecified sites of the carotid artery tree during 3 years of follow-up. The IMT of internal carotid artery, at the site of maximum stenosis, increased significantly from 0 mm after 24 hours, to 0.41 mm at 3 months, to 0.48 mm at 6 months, and to 0.51 mm at 3 years of follow-up. In the same site, diameters and residual stenosis (range 29-24%) did not change over time. Our study showed that stent is self-expanding against the atherosclerotic plaque within the 3-year follow-up period. Despite neointima formation, the intima-intima diameter does not change without worsening of the residual stenosis.

Role of Stents, Drug-Eluting Stents, and Stent-Grafts in Treatment of Infrainguinal Arterial Disease

Infrainguinal peripheral arterial disease is increasingly treatable by endovascular techniques. Bare-metal, drug-eluting, and covered stents (stent-grafts) are increasingly important adjuncts to percutaneous transluminal angioplasty in the treatment of occlusive and aneurysmal disease. Preliminary data suggest bioabsorbable stents may also have a significant clinical impact as well. In this article, we describe the available evidence supporting use of stents in the femoropopliteal and tibial arteries, as well as some of their limitations and complications.

Stent fracture in revascularization for symptomatic ostial vertebral artery stenosis

INTRODUCTION

We assessed the long-term follow-up examinations and complications of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic ostial vertebral artery (VA) stenosis.

METHODS

A retrospective study was done to evaluate 12 patients with symptomatic ostial VA stenosis who underwent PTAS. Six patients were treated with the Palmaz stent and six with a balloon-expandable coronary stent. Initial angiographic follow-up examination was conducted about 12 months after PTAS in all patients. Simple radiographic, ultrasonographic and clinical follow-up examinations were scheduled every 6 months.

RESULTS

Excellent dilatation was achieved in all patients without any procedural complications. Initial angiographic follow-up obtained at a mean of 13 months after PTAS detected no restenosis. However, an asymptomatic severe restenosis was detected at 24 months after PTAS in one patient (8%). During a mean follow-up of 31.5 months, three stent fractures were detected in deployed coronary stents (50%). None of the stent fractures was associated with either recurrent stroke or restenosis. No patients developed recurrent symptoms during the follow-up period.

CONCLUSION

PTAS for symptomatic ostial VA stenosis is effective in preventing recurrent stroke. As the open-cell single-joint type of stent is associated with the risk of fracture, long-term follow-up examinations including simple radiography are needed.

Delayed deformation of self-expanding stents after carotid artery stenting for postendarterectomy restenoses

Carotid artery stenting has become an acceptable alternative for treating patients with severe atherosclerotic lesions, particularly those with significant surgical risks, such as recurrent stenosis after endarterectomy. Stent deformation, a phenomenon primarily associated with balloon-expandable stents, is largely avoided by exclusively using self-expanding stents in treating carotid artery stenosis. Nonetheless, we herein report two patients who presented with delayed Wallstent deformation after carotid artery stenting for postendarterectomy restenosis. Our cases highlight the need for caution because delayed deformation of self-expanding stents can occur, particularly during treatment of patients with postendarterectomy stenosis. Furthermore, poststent surveillance is imperative in identifying patients with severe restenosis after carotid artery stenting who need reintervention.

A case of popliteal stent fracture with pseudoaneurysm formation

We describe a case of angiographically documented stent fracture and pseudoaneurysm formation in a patient with femoropopliteal disease, which was successfully treated with deployment of an endovascular stent graft. Technical aspects of the procedure are discussed and the experience with stent fractures previously reported in the literature is reviewed.

Limitations of percutaneous transluminal angioplasty and stenting for the treatment of disease of the superficial femoral and popliteal arteries

The long-term primary patency rates for percutaneous transluminal angioplasty (PTA) and stenting in treatment of disease of the superficial femoral and popliteal arteries have been disappointing. Three-year primary patency rates of approximately 50% have been reported for PTA and first-generation stents. Early results with newer nitinol stents appear promising; however, long-term data are lacking. One- and 2-year primary patency rates of 76% to 97% and 60% to 84%, respectively, have been reported with nitinol stents. An emerging concern with nitinol stents is the frequency of stent fracture (> or = 25%) after interventions for long-segment disease. A recent study has shown that stent fractures are associated with in-stent restenosis and with significantly lower primary patency at 1 year. The therapeutic success of PTA and stenting correlates with the complexity of the underlying disease. The best results are achieved when treating focal stenoses in patients with good distal runoff. Because endovascular interventions are preferred by patients, can be repeated, and preserve the option of bypass surgery, PTA and stenting are increasingly employed for diffuse and complex SFA disease. Clarifying the role of PTA and stenting in the treatment of complex SFA disease will require future studies that stratify results by both lesion anatomy and treatment indication.

A clinical survey of vascular stents

As a result of the many different potential locations to be treated, it is still difficult to evaluate the indications for efficacy and safety of non-coronary percutaneous transluminal angioplasty (PTA) and stenting versus surgical methods, such as endarterectomy or bypass grafts. This paper reviews pertinent data published in the last 5-10 years and gives an overview of the main peripheral minimally invasive vascular interventional fields.